The present invention relates to an automatic vehicle speed control system.
Automatic vehicle speed control systems known in the art comprise a speed control mechanism which controls an input variable of the vehicle engine according to a feedback control signal which is derived from a controller as an indication of the deviation of the vehicle speed from a reference setting.
There is a general tendency in recent years toward installing a variety of additional control functions which are economically made possible by the introduction of high technology electronic circuits. These additional functions include, for example, a diagnostic feature that examines the various components of the vehicle to give an early warning if a failing part is detected, an automatic navigator that allows the vehicle occupant to follow the directions given by computer-derived information, and automatic vehicle speed control that generates speed change signals in cooperation with an automatic power transmission. This inevitably results in an increase in the necessary keys and switches which must be arranged on the instrument panel and also gives rise to reliability problems. To meet the space limitations of the instrument panel and to the increasing instances of failure, provision is made to assign dual functions to a single switch to minimize the number of components and the space to be occupied. It is also required that such systems be designed from the safety standpoint and reliable components be used throughout the system.